Yoshimitsu CE Fail

Yeah that's one good guess. It has to be the front and not the side to connect. I should test it out just to give some Yoshis things to look out for while playing as one haha.

I haven't tested it yet but I think it might have something to do with Yoshi's CE's hitbox. While the hitbox obviously hits from the side, it may not have CE initiation properties unless it connects from the front. That's my guess anyways since you can see that Astaroth stepped and got hit by Yoshi's side.

This happens to me quite a bit. I may need to research on this sometime soon...